1. Field of the Present Invention
The present invention relates to a stabilization method of a cycloalkanone oxime.
2. Description of the Related Art
Since a cycloalkanone oxime is thermally instable, a variety of methods of improving its thermal stability have been proposed, such as a method of allowing an alkali metal or alkaline earth metal, or an oxide, a hydroxide or an alcoholate of an alkali metal, alkaline earth metal, zinc or aluminum to be existed in a gasification region of a cycloalkanone oxime (see, Japanese Patent Application Publication No. 47-41909);
a method of washing a molten cycloalkanone oxime with an aqueous ammonium sulfate solution and keeping pH at 4.5 to 5.8 (see, Japanese Patent Application Laid-Open No. 2-193957);
a method of allowing ammonia or a lower alkyl amine to be existed in an cycloalkanone oxime (see, Japanese Patent Application Laid-Open No. 5-186409); and
a method of washing a cycloalkanone oxime solution with water or an aqueous basic solution and a method of passing a cycloalkanone oxime solution through a weakly alkaline ion exchange resin (see, Japanese Patent Application Laid-Open No. 2003-34674).